1. Field of the Invention
The present invention relates to cooling heat generated in a connection portion through which illuminating light enters an endoscope when the illuminating light from an external light source is guided into the endoscope.
2. Description of the Related Art
In the case of endoscopes which are widely used in medical fields and industrial fields, target areas to be diagnosed or observed are in the insides of living bodies, plants and the like. For this reason, the target areas to be observed need to be illuminated. A general endoscope apparatus is provided with a light source device as an accessory device for an endoscope, and is constructed to guide illuminating light irradiated from an illuminating lamp inside the light source device, to an illuminating guide fiber provided in the endoscope. This illuminating light exits from an illuminating window provided at the tip end of an inserting part of the endoscope, and illuminates an area to be observed.
An example of the light source device is a high-luminance light source device which includes a high-luminance illuminating lamp, a lighting driving circuit for lighting and controlling this illuminating lamp by means of commercial power, and a light guide cable for guiding illuminating light projected from the illuminating lamp.
In recent years, it has become popular to use a small-sized battery-driven light source device that powers an illuminating lamp by using a battery such as a dry battery.
Portable endoscopes have been widely used. A portable endoscope is constructed to allow the high-luminance light source device and the battery-driven light source device to be removably connected to the endoscope, and is easily portably constructed so that endoscopic observation can be performed by using the battery-driven light source device even in the case where commercial power is difficult to use.
In the case where such a light source device (high-luminance light source device, battery-driven light source device, or other light source device) is connected to an endoscope and illuminating light from the light source device is guided into the endoscope, light losses occur as heat in a connection portion between the light source device and a manipulating part of the endoscope. Particularly in the case where the amount of illuminating light is large as in the high-luminance light source device, the vicinity of the connecting portion for connecting the light source device to the endoscope (light source connecting portion) is heated and becomes hot. Even if the heated portion is formed of a heat resistant member, it is difficult for a user to manipulate the endoscope without touching the heated portion. In the case of the battery-driven light source device as well, when a larger amount of illuminating light is to be obtained, the lighting driving power of the illuminating lamp needs to be made higher, so that a temperature rise occurs in the light source connecting portion.
In addition, in the case where the distance between the illuminating lamp and the light source connecting portion is short as in the battery-driven light source device, the heat radiation of the illuminating lamp becomes insufficient owing to a temperature rise of the light source connecting portion, which may also decrease the life of the illuminating lamp. Furthermore, in the case where the illuminating lamp burns out during the use of the endoscope, there may be a case where lamp replacing work is difficult to perform quickly, owing to the influence of a temperature rise of the light source connecting portion.
Several measures to cope with the generation of heat due to light losses in the light source connecting portion in the manipulating part of the endoscope are disclosed in JP-A-2000-121960. A first embodiment of JP-A-2000-121960 proposes the shape of alight source connecting portion which a user cannot easily touch during manipulation of the endoscope. A second embodiment proposes that a small hole be formed in a connecting portion to which an air supply tube is to be connected, so that air expelled through this small hole is applied to the light source connecting portion from the outside to cool the light source connecting portion.